Preamble based uplink power control for LTE

ABSTRACT

Systems and methodologies are described that facilitate utilizing power control preambles with closed loop power control techniques in a wireless communication environment. An uplink grant can be transferred over a downlink (e.g., a first uplink grant after uplink inactivity), and a power control preamble can be sent over an uplink in response to the uplink grant. According to an example, transmission of the power control preamble can be explicitly scheduled and/or implicitly scheduled. The power control preamble can be transmitted at a power level determined by an access terminal utilizing an open loop power control mechanism. A base station can analyze the power control preamble and generate a power control command based thereupon to correct the power level employed by the access terminal. The access terminal can thereafter utilize the power control command to adjust the power level for uplink data transmission.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/030,333, entitled PREAMBLE BASED UPLINK POWER CONTROL FOR LTE, filedFeb. 13, 2008, which claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/889,931, entitled A METHOD AND APPARATUS FORPOWER CONTROL USING A POWER CONTROL PREAMBLE, filed Feb. 14, 2007, bothof which are incorporated by reference in their entirety.

FIELD

The following description relates generally to wireless communications,and more particularly to controlling uplink (UL) power levels employedby access terminals in a Long Term Evolution (LTE) based wirelesscommunication system.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustypes of communication; for instance, voice and/or data can be providedvia such wireless communication systems. A typical wirelesscommunication system, or network, can provide multiple users access toone or more shared resources (e.g., bandwidth, transmit power, etc.).For instance, a system can use a variety of multiple access techniquessuch as Frequency Division Multiplexing (FDM), Time DivisionMultiplexing (TDM), Code Division Multiplexing (CDM), OrthogonalFrequency Division Multiplexing (OFDM), Single Carrier FrequencyDivision Multiplexing (SC-FDM), and others. Additionally, the system canconform to specifications such as third generation partnership project(3GPP), 3GPP long term evolution (LTE), etc.

Generally, wireless multiple-access communication systems cansimultaneously support communication for multiple access terminals. Eachaccess terminal can communicate with one or more base stations viatransmissions on forward and reverse links. The forward link (ordownlink) refers to the communication link from base stations to accessterminals, and the reverse link (or uplink) refers to the communicationlink from access terminals to base stations. This communication link canbe established via a single-input-single-output (SISO),multiple-input-single-output (MISO), single-input-multiple-output (SIMO)or a multiple-input-multiple-output (MIMO) system.

Wireless communication systems oftentimes employ one or more basestations and sectors therein that provide a coverage area. A typicalsector can transmit multiple data streams for broadcast, multicastand/or unicast services, wherein a data stream may be a stream of datathat can be of independent reception interest to an access terminal. Anaccess terminal within the coverage area of such sector can be employedto receive one, more than one, or all the data streams carried by thecomposite stream. Likewise, an access terminal can transmit data to thebase station or another access terminal. With many access terminalstransmitting signal data in proximity, power control is important foryielding sufficient signal to noise ratios (SNRs) at different datarates and transmission bandwidths for communications over the uplink. Itis desirable to keep the overhead incurred from the transmission of thepower adjustments to these access terminals as low as possible whileachieving the aforementioned goals. The reduction in the overhead insupport of power control adjustments make it difficult to guarantee anadequate reception reliability level in all situations, and most notablyin situations with extended periods of data inactivity in the UL.

SUMMARY

The following presents a simplified summary of one or more embodimentsin order to provide a basic understanding of such embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements of allembodiments nor delineate the scope of any or all embodiments. Its solepurpose is to present some concepts of one or more embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

In accordance with one or more embodiments and corresponding disclosurethereof, various aspects are described in connection with facilitatingutilization of power control preambles with aperiodic closed loop powercontrol techniques in a wireless communication environment. An uplinkgrant can be transferred over a downlink (e.g., a first uplink grantafter uplink inactivity), and a power control preamble can be sent overan uplink in response to the uplink grant. According to an example,transmission of the power control preamble can be explicitly scheduledand/or implicitly scheduled. The power control preamble can betransmitted at a power level determined by an access terminal utilizingan open loop power control mechanism. A base station can analyze thepower control preamble and generate a power control command basedthereupon to correct the power level employed by the access terminal.The access terminal can thereafter utilize the power control command toadjust the power level for uplink data transmission.

According to related aspects, a method that facilitates generating apower control preamble for utilization in a wireless communicationenvironment is described herein. The method can include receiving anuplink grant from a base station, the uplink grant being a first uplinkgrant after uplink inactivity. Further, the method can comprisetransmitting a power control preamble to the base station with a powersetting based on open loop power control. Moreover, the method caninclude receiving a power control command from the base station, thepower control command adjusts the power setting. The method can alsoinclude transmitting data to the base station with the adjusted powersetting.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus can include a memory that retainsinstructions related to obtaining an uplink grant from a base station,the uplink grant being a first uplink grant after uplink inactivity,determining a power level for power control preamble transmission basedupon an open loop evaluation, sending a power control preamble to thebase station at the power level, receiving a power control command fromthe base station, altering the power level based upon the power controlcommand, and sending an uplink data transmission to the base station ata power level that has been altered in accordance to the power controlcommand. Further, the wireless communications apparatus can include aprocessor, coupled to the memory, configured to execute the instructionsretained in the memory.

Yet another aspect relates to a wireless communications apparatus thatenables utilizing power control preambles in a wireless communicationenvironment. The wireless communications apparatus can include means forobtaining an uplink grant, the uplink grant being a first uplinksubsequent to uplink inactivity. Further, the wireless communicationsapparatus can include means for transferring an uplink power controlpreamble at a power level selected as a function of an open loop powercontrol estimate. Moreover, the wireless communications apparatus cancomprise means for obtaining a power control command that alters thepower level. Additionally, the wireless communications apparatus caninclude means for transmitting uplink data at the altered power level.

Still another aspect relates to a machine-readable medium having storedthereon machine-executable instructions for obtaining an uplink grant,the uplink grant being a first uplink grant after uplink inactivity;transferring an uplink power control preamble at a power level selectedas a function of an open loop power control estimate; obtaining a powercontrol command that alters the power level; and transmitting uplinkdata at the altered power level.

In accordance with another aspect, an apparatus in a wirelesscommunication system can include a processor, wherein the processor canbe configured to obtain an uplink grant from a base station, the uplinkgrant being a first uplink grant subsequent to uplink inactivity.Further, the processor can be configured to determine a power level forpower control preamble transmission based upon an open loop evaluation.The processor can also be configured to send a power control preamble tothe base station at the power level. Moreover, the processor can beconfigured to receive a power control command from the base station.Additionally, the processor can be configured to alter the power levelbased upon the power control command. Further, the processor can beconfigured to send an uplink data transmission to the base station atthe altered power level.

According to other aspects, a method that facilitates evaluating powercontrol preambles for employment with power control in a wirelesscommunication environment is described herein. The method can includetransmitting an uplink grant to an access terminal. Further, the methodcan include receiving a power control preamble sent from the accessterminal at a power level set based upon open loop power control.Moreover, the method can comprise generating a power control commandbased upon an analysis of the power control preamble, the power controlcommand corrects the power level of the access terminal. The method canalso include transmitting the power control command to the accessterminal. Additionally, the method can include receiving an uplink datatransmission sent from the access terminal at the corrected power level.

Yet another aspect relates to a wireless communications apparatus thatcan include a memory that retains instructions related to transferringan uplink grant, obtaining a power control preamble sent via an uplinkat a power level determined by an open loop power control mechanism,yielding a power control command that corrects the power level basedupon an evaluation of the power control preamble, sending the powercontrol command via a downlink, and obtaining an uplink datatransmission sent at the corrected power level. Further, the wirelesscommunications apparatus can comprise a processor, coupled to thememory, configured to execute the instructions retained in the memory.

Another aspect relates to a wireless communications apparatus thatenables yielding power control commands based upon power controlpreambles for utilization by access terminals in wireless communicationenvironment. The wireless communications apparatus can include means forsending an uplink grant over a downlink. Moreover, the wirelesscommunications apparatus can include means for obtaining a power controlpreamble sent at a power level determined from an open loop estimate.The wireless communications apparatus can additionally comprise meansfor sending a power control command that corrects the power level.Further, the wireless communications apparatus can include means forobtaining an uplink data transmission at the corrected power level.

Still another aspect relates to a machine-readable medium having storedthereon machine-executable instructions for sending an uplink grant overa downlink; obtaining a power control preamble sent at a power leveldetermined from an open loop estimate; sending a power control commandthat corrects the power level; and obtaining an uplink data transmissionat the corrected power level.

In accordance with another aspect, an apparatus in a wirelesscommunication system can include a processor, wherein the processor canbe configured to transmit an uplink grant to an access terminal. Theprocessor can also be configured to receive a power control preamblesent from the access terminal at a power level set based upon open looppower control. Further, the processor can be configured to generate apower control command based upon an analysis of the power controlpreamble, the power control command corrects the power level of theaccess terminal. Moreover, the processor can be configured to transmitthe power control command to the access terminal. Additionally, theprocessor can be configured to receive an uplink data transmission sentfrom the access terminal at the corrected power level.

To the accomplishment of the foregoing and related ends, the one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe one or more embodiments. These aspects are indicative, however, ofbut a few of the various ways in which the principles of variousembodiments can be employed and the described embodiments are intendedto include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a wireless communication system inaccordance with various aspects set forth herein.

FIG. 2 is an illustration of an example system that controls uplinkpower level(s) employed by access terminal(s) in an LTE based wirelesscommunication environment.

FIG. 3 is an illustration of an example system that periodicallycorrects an uplink power level employed by an access terminal.

FIG. 4 is an illustration of an example system that aperiodicallytransfers power control commands to access terminals in an LTE basedwireless communication environment.

FIG. 5 is an illustration of an example system that employs preamblebased uplink power control in an LTE based wireless communicationenvironment.

FIG. 6 is an illustration of an example system that groups accessterminals for sending power control commands over a downlink.

FIG. 7 is an illustration of example transmission structures forcommunicating power control commands to access terminal groups.

FIG. 8 is an illustration of an example timing diagram for a periodicuplink power control procedure for LTE.

FIG. 9 is an illustration of an example timing diagram for an aperiodicuplink power control procedure for LTE.

FIG. 10 is an illustration of an example timing diagram for an uplinkpower control procedure for LTE that leverages a power control preamble.

FIG. 11 is an illustration of an example methodology that facilitatesgenerating a power control preamble for utilization with power controlin a Long Term Evolution (LTE) based wireless communication environment.

FIG. 12 is an illustration of an example methodology that facilitatesevaluating power control preambles for employment with power control ina Long Term Evolution (LTE) based wireless communication environment.

FIG. 13 is an illustration of an example access terminal thatfacilitates utilizing power control preambles with power control in anLTE based wireless communication system.

FIG. 14 is an illustration of an example system that facilitatesanalyzing power control preambles for use with power control in an LTEbased wireless communication environment.

FIG. 15 is an illustration of an example wireless network environmentthat can be employed in conjunction with the various systems and methodsdescribed herein.

FIG. 16 is an illustration of an example system that enables yieldingpower control commands based upon power control preambles forutilization by access terminals in a wireless communication environment.

FIG. 17 is an illustration of an example system that enables utilizingpower control preambles in a wireless communication environment.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component can be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component can be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components can communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

Furthermore, various embodiments are described herein in connection withan access terminal. An access terminal can also be called a system,subscriber unit, subscriber station, mobile station, mobile, remotestation, remote terminal, mobile device, user terminal, terminal,wireless communication device, user agent, user device, or userequipment (UE). An access terminal can be a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, computing device,or other processing device connected to a wireless modem. Moreover,various embodiments are described herein in connection with a basestation. A base station can be utilized for communicating with accessterminal(s) and can also be referred to as an access point, Node B,eNode B (eNB), or some other terminology.

Moreover, various aspects or features described herein can beimplemented as a method, apparatus, or article of manufacture usingstandard programming and/or engineering techniques. The term “article ofmanufacture” as used herein is intended to encompass a computer programaccessible from any computer-readable device, carrier, or media. Forexample, computer-readable media can include but are not limited tomagnetic storage devices (e.g., hard disk, floppy disk, magnetic strips,etc.), optical disks (e.g., compact disk (CD), digital versatile disk(DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card,stick, key drive, etc.). Additionally, various storage media describedherein can represent one or more devices and/or other machine-readablemedia for storing information. The term “machine-readable medium” caninclude, without being limited to, wireless channels and various othermedia capable of storing, containing, and/or carrying instruction(s)and/or data.

Referring now to FIG. 1, a wireless communication system 100 isillustrated in accordance with various embodiments presented herein.System 100 comprises a base station 102 that can include multipleantenna groups. For example, one antenna group can include antennas 104and 106, another group can comprise antennas 108 and 110, and anadditional group can include antennas 112 and 114. Two antennas areillustrated for each antenna group; however, more or fewer antennas canbe utilized for each group. Base station 102 can additionally include atransmitter chain and a receiver chain, each of which can in turncomprise a plurality of components associated with signal transmissionand reception (e.g., processors, modulators, multiplexers, demodulators,demultiplexers, antennas, etc.), as will be appreciated by one skilledin the art.

The corresponding sector of base station 102 can communicate with one ormore access terminals such as access terminal 116 and access terminal122; however, it is to be appreciated that base station 102 cancommunicate with substantially any number of access terminals similar toaccess terminals 116 and 122. Access terminals 116 and 122 can be, forexample, cellular phones, smart phones, laptops, handheld communicationdevices, handheld computing devices, satellite radios, globalpositioning systems, PDAs, and/or any other suitable device forcommunicating over wireless communication system 100. As depicted,access terminal 116 is in communication with antennas 112 and 114, whereantennas 112 and 114 transmit information to access terminal 116 over aforward link 118 and receive information from access terminal 116 over areverse link 120. Moreover, access terminal 122 is in communication withantennas 104 and 106, where antennas 104 and 106 transmit information toaccess terminal 122 over a forward link 124 and receive information fromaccess terminal 122 over a reverse link 126. In a frequency divisionduplex (FDD) system, forward link 118 can utilize a different frequencyband than that used by reverse link 120, and forward link 124 can employa different frequency band than that employed by reverse link 126, forexample. Further, in a time division duplex (TDD) system, forward link118 and reverse link 120 can utilize a common frequency band and forwardlink 124 and reverse link 126 can utilize a common frequency band.

Each group of antennas and/or the area in which they are designated tocommunicate can be referred to as a sector of base station 102, or as acell of an eNB. For example, antenna groups can be designed tocommunicate to access terminals in a sector of the areas covered by basestation 102. In communication over forward links 118 and 124, thetransmitting antennas of base station 102 can utilize beamforming toimprove signal-to-noise ratio of forward links 118 and 124 for accessterminals 116 and 122. Also, while base station 102 utilizes beamformingto transmit to access terminals 116 and 122 scattered randomly throughan associated coverage, access terminals in neighboring cells can besubject to less interference as compared to a base station transmittingthrough a single antenna to all its access terminals.

System 100 can be a Long Term Evolution (LTE) based system, forinstance. In such system 100, the corresponding sectors of base station102 can control uplink power levels utilized by access terminals 116 and122. Hence, system 100 can provide uplink (UL) power control whichyields compensation of path loss and shadowing (e.g., path loss andshadowing can slowly change over time) and compensation of time-varyinginterference from adjacent cells (e.g., since system 100 can be an LTEbased system that utilizes frequency reuse 1). Moreover, system 100 canmitigate large variations of receive power obtained at base station 102across users (e.g., since the users can be multiplexed within a commonband). Further, system 100 can compensate for multipath fadingvariations at sufficiently low speeds. For instance, the coherence timeof the channel for 3 km/h at different carrier frequencies can be asfollows: a carrier frequency of 900 MHz can have a coherence time of 400ms, a carrier frequency of 2 GHz can have a coherence time of 180 ms,and a carrier frequency of 3 GHz can have a coherence time of 120 ms.Thus, depending on latency and periodicity of adjustments, fast fadingeffects can be corrected with low Doppler frequencies.

System 100 can employ uplink power control that combines open loop andclosed loop power control mechanisms. According to an example, open looppower control can be utilized by each access terminal 116, 122 forsetting power levels of a first preamble of a Random Access Channel(RACH) communication. For the first preamble of a RACH, each accessterminal 116, 122 may have obtained downlink (DL) communication(s) frombase station 102, and the open loop mechanism can enable each accessterminal 116, 122 to select an uplink transmit power level that isinversely proportional to a receive power level related to the obtaineddownlink communication(s). Thus, knowledge of the downlink can beutilized by access terminals 116, 122 for uplink transmissions. The openloop mechanism can allow for very fast adaptation to severe changes ofradio conditions (e.g., depending on receive power filtering) by way ofinstantaneous power adjustments. Further, the open loop mechanism cancontinue to operate beyond the RACH processing in contrast toconventional techniques oftentimes employed. The closed loop mechanismcan be utilized by system 100 once the random access procedure hassucceeded. For example, closed loop techniques can be employed whenperiodic uplink resources have been allocated to access terminals 116,122 (e.g., the periodic uplink resources can be Physical Uplink ControlChannel (PUCCH) or Sounding Reference Signal (SRS) resources). Moreover,the corresponding sectors in base station 102 (and/or a network) cancontrol uplink transmit power utilized by access terminals 116, 122based upon the closed loop control.

The closed loop mechanism employed by system 100 can be periodic,aperiodic or a combination of the two. Periodic closed-loop correctionscan be transmitted by the corresponding sectors in base station 102 toaccess terminals 116, 122 periodically (e.g., once every 0.5 ms, 1 ms, 2ms, 4 ms, . . . ). For instance, the periodicity can be dependent uponperiodicity of uplink transmissions. Moreover, the periodic correctionscan be single-bit corrections (e.g., up/down, ±1 dB, . . . ) and/ormulti-bit corrections (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ). Thus,the power control step and the periodicity of corrections can determinea maximum rate of change of uplink power that the corresponding sectorsin base station 102 (and/or the network) can control. According toanother example, aperiodic corrections can be sent from thecorresponding sectors in base station 102 to corresponding accessterminals 116, 122 as needed. Following this example, these correctionscan be transmitted aperiodically when triggered by a network measurement(e.g., receive (RX) power outside a set margin, opportunity to sendcontrol information to a given access terminal, . . . ). Moreover,aperiodic corrections can be single-bit and/or multi-bit (e.g., thecorrections can be multi-bit since a significant portion of overheadassociated with aperiodic corrections can relate to correctionscheduling rather than correction size). According to yet anotherexample, the aperiodic corrections can be transmitted by thecorresponding sector in base station 102 to access terminals 116, 122 inaddition to periodic corrections in order to minimize the overheadincurred with the transmission of these power adjustments.

Now turning to FIG. 2, illustrated is a system 200 that controls uplinkpower level(s) employed by access terminal(s) in an LTE based wirelesscommunication environment. System 200 includes a sector in a basestation 202 that can communicate with substantially any number of accessterminal(s) (not shown). Moreover, the sector in base station 202 caninclude a received power monitor 204 that evaluates power level(s)associated with uplink signal(s) obtained from access terminal(s).Further, the sector in base station 202 can comprise an uplink (UL)power adjuster 206 that utilizes the analyzed power level(s) to generatecommand(s) to alter access terminal power levels.

Various physical (PHY) channels 208 can be leveraged for communicationbetween base station 202 and the access terminal(s); these physicalchannels 208 can include downlink physical channels and uplink physicalchannels. Examples of downlink physical channels include PhysicalDownlink Control Channel (PDCCH), Physical Downlink Shared Channel(PDSCH), and Common Power Control Channel (CPCCH). PDCCH is a DL layer1/layer 2 (L1/L2) control channel (e.g., assigning PHY layer resourcesfor DL or UL transmission) that has a capacity of around 30-60 bits andis cyclic redundancy check (CRC) protected. PDCCH can carry uplinkgrants and downlink assignments. PDSCH is a DL shared data channel;PDSCH can be a DL data channel shared amongst different users. CPCCH istransmitted on the DL for UL power controlling multiple accessterminals. Corrections sent on the CPCCH can be single-bit or multi-bit.Further, the CPCCH can be a particular instantiation of the PDCCH.Examples of uplink physical channels include Physical Uplink ControlChannel (PUCCH), Physical Uplink Shared Channel (PUSCH), SoundingReference Signal (SRS), and Random Access Channel (RACH). PUCCH includesthe Channel Quality Indicator (CQI) channel, the ACK channel and the ULrequests. PUSCH is an UL shared data channel. The SRS can lackinformation and can enable sounding the channel on the UL to allow forthe channel to be sampled over part of the full system bandwidth. It isto be appreciated that the claimed subject matter is not limited tothese example physical channels 208.

Received power monitor 204 and UL power adjuster 206 can provide closedloop power control for uplink transmissions effectuated by accessterminal(s). Operation on the LTE system can entail transmissions at agiven time over bandwidths that can be significantly less than theentirety of the bandwidth of system 200. Each access terminal cantransmit over a small portion of the entire bandwidth of system 200 at agiven time. Moreover, frequency hopping can be employed by the accessterminals; thus, the corresponding sector in base station 202 canencounter difficulty when attempting to evaluate adjustments to make touplink power levels of the access terminals. Therefore, an adequateclosed loop power control mechanism provided by received power monitor204 and UL power adjuster 206 constructs a wideband receive powerestimate from transmissions over possibly multiple instants and onpossibly multiple UL PHY channels enabling adequate correction of thepath loss and shadowing effects irrespective of access terminaltransmission bandwidth at any time.

Received power monitor 204 constructs the wideband receive powerestimate from the sampling of the channel based upon access terminaltransmissions in a variety of manners. For instance, received powermonitor 204 can employ the PUSCH for sampling. Following this example,the transmission band of the PUSCH is localized on a given slot.Frequency diverse scheduling can apply a pseudo-random hopping patternto the transmission band at slot boundaries and possibly overre-transmissions to fully exploit the frequency diversity. PUSCHtransmissions exploiting frequency selective scheduling will not apply afrequency hopping pattern onto the transmit data and therefore mayrequire a long time in order to sample the channel at all (or most)frequencies. Moreover, frequency selective scheduling can leveragetransmission of an SRS or PUCCH. Frequency selective scheduling is ascheduling strategy exploiting the selectivity of the channel; forinstance, frequency selective scheduling attempts to confinetransmissions onto the best sub-bands. This scheduling strategy can berelevant for low mobility access terminals. Further, these transmissionsare usually exclusive of frequency hopping techniques. Frequency diversescheduling is a disparate scheduling strategy employing the entiresystem bandwidth (e.g., modulo the minimum transmit bandwidthcapability, . . . ) to naturally obtain frequency diversity.Transmissions associated with frequency diverse scheduling can beassociated with frequency hopping. Moreover, frequency hopping caninclude changing the transmit frequency of a waveform in a pseudo-randommanner to exploit frequency diversity from the point of view of achannel as well as interference.

According to another example, received power monitor 204 can utilize thePUCCH for sampling the UL channel and therefore to construct thewideband receive power estimate. The transmission band of the PUCCH canalso be localized on a given slot with hopping at the slot boundary oneach transmission time interval (TTI). An occupied band can depend onwhether there is PUSCH transmission on a particular TTI. When PUSCH istransmitted over a given TTI, the control information that would betransmitted over PUCCH can be transmitted in-band with the remainder ofthe data transmission (e.g., to retain the single-carrier property ofthe UL waveform) over PUSCH. When PUSCH is not transmitted over aparticular TTI, the PUCCH can be transmitted over a localized band setaside for transmission of the PUCCH at the edges of the system band.

Pursuant to another illustration, SRS transmissions can be utilized byreceived power monitor 204 to sample the channel and construct thewideband receive power estimate. The transmission band (over time) ofthe SRS can be substantially equal to the entire system band (or theminimum access terminal transmit bandwidth capability). At a givenSC-FDMA symbol (e.g., SC-FDMA symbol is a minimum unit of transmissionon the UL of LTE), the transmission can be localized (e.g., spanning aset of consecutive subcarriers that hops over time) or distributed(e.g., spanning the entire system band or a portion thereof, which mayor may not hop, . . . ).

Received power monitor 204 constructs the wideband receive powerestimate from sampling of the channel over the entire system bandwidth.However, depending upon the manner by which the channel is sampledand/or whether frequency hopping is applied to the transmissions, thetime span to construct the wideband receive power estimate from thesampling of the UL channel by received power monitor 204 can vary.

PUCCH transmissions when there is no UL data take place at the edges ofthe system band. PUCCH transmission where there is UL data can belocated in-band with the data transmission over the PUSCH. Further,PUSCH transmissions may not change transmit frequency or may not behopping at all to exploit UL frequency selective scheduling; however, toenable frequency selective scheduling, SRS transmissions can beleveraged for FDD/TDD systems. Moreover, when the PUSCH uses frequencydiverse scheduling, frequency hopping is applied to transmissions.

Moreover, based upon the channel sampling effectuated by received powermonitor 204, UL power adjuster 206 can generate a command that can alterthe UL power level employed by a particular access terminal. The commandcan be a single-bit correction (e.g., up/down, ±1 dB, . . . ) and/or amulti-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ).Further, UL power adjuster 206 (and/or the sector in the correspondingbase station 202) can transmit the generated command to the accessterminal to which the command is intended.

Further, the access terminal(s) can each be associated with a particularstate at a given time. Examples of access terminal states includeLTE_IDLE, LTE_ACTIVE and LTE_ACTIVE_CPC. However, it is to beappreciated that the claimed subject matter is not limited to theseillustrative states.

LTE_IDLE is an access terminal state where the access terminal does nothave a unique cell ID. While in the LTE_IDLE state, the access terminalcan lack a connection to base station 202. Further, transitioning toLTE_ACTIVE state from LTE_IDLE can be effectuated via utilization ofRACH.

LTE_ACTIVE is an access terminal state where the access terminal has aunique cell ID. Further, when in LTE_ACTIVE state, the access terminalcan actively transfer data via the uplink and/or downlink. Accessterminals in this state have UL dedicated resources (e.g., CQI, SRS thatare transmitted periodically, . . . ). According to an example, accessterminals in the LTE_ACTIVE state can employ discontinuoustransmission/discontinuous reception (DTX/DRX) procedures with a cyclethat is not expected to be much longer than approximately 20 ms or 40ms. Access terminals in this state start PUSCH transmissions eitherdirectly in response to DL activity (e.g., with possibly an UL grantin-band with DL data or through the PDCCH) or by sending an UL requestover the PUCCH. Further, users in this state can be access terminalswith an active exchange of UL/DL data taking place or access terminalsrunning a high Grade of Service (GoS) application (e.g., Voice overInternet Protocol (VoIP), . . . ).

LTE_ACTIVE_CPC (Continuous Packet Connectivity) is a substate ofLTE_ACTIVE where access terminals retain their unique cell ID but wherethe UL dedicated resources have been released. Utilization ofLTE_ACTIVE_CPC enables extending battery life. Access terminals in thissubstate start transmissions either in response to DL activity (e.g.,with possibly an UL grant in-band with DL data or through the PDCCH, . .. ) or by sending an UL request over the RACH. The initial transmitpower can be either based on an open loop mechanism (e.g., response toDL activity) or a last successful preamble (e.g., RACH).

Referring to FIG. 3, illustrated is a system 300 that periodicallycorrects an uplink power level employed by an access terminal System 300includes base station 202 that communicates with an access terminal 302(and/or any number of disparate access terminals (not shown)). Accessterminal 302 comprises an UL power manager 304, which further includesan UL power initializer 306. Moreover, access terminal 302 includes anUL periodic transmitter 308. Base station 202 further includes receivedpower monitor 204 and UL power adjuster 206; UL power adjuster 206further comprises a periodic corrector 310.

Periodic corrector 310 generates periodic power control commands (e.g.,periodic transmission power control (TPC) commands, periodiccorrections, . . . ) to be transferred to access terminal 302. Further,periodic corrector 310 can transmit the periodic power control commandsto access terminal 302 (and/or any disparate access terminal(s)) withany periodicity (e.g., 0.5 ms, 1 ms, 2, ms, 4 ms, . . . ); however, itis contemplated that UL power adjuster 206 and/or base station 202 cantransmit such periodic power control commands. Further, periodiccorrector 310 can yield a single-bit correction (e.g., up/down, ±1 dB, .. . ) and/or a multi-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, .. . ). For example, if the periodic corrections are sent from periodiccorrector 310 at a higher frequency, then single-bit corrections can bemore likely to be employed, and vice versa.

UL power manager 304 controls the uplink power level employed by accessterminal 302 for uplink transmissions. UL power manager 304 can receivethe periodic power control commands from base station 202 and alter theuplink power level utilized for transmission based upon the obtainedcommands. According to another illustration, UL power initializer 306can set an initial uplink transmit power. UL power initializer 306 canemploy an open loop mechanism to determine the initial uplink transmitpower based upon downlink activity, for example. Additionally oralternatively, UL power initializer 306 can assign the initial uplinkpower level to a power level associated with a previous (e.g.,immediately prior, etc.) successful preamble (e.g., RACH).

UL periodic transmitter 308 can send periodic transmissions over theuplink to base station 202. For instance, UL periodic transmitter 308can operate while access terminal 302 is in LTE_ACTIVE state. Moreover,the periodic transmissions transferred by UL periodic transmitter 308can be a set of SRS transmissions; however, it is to be appreciated thatthe claimed subject matter is not so limited as any type of periodicuplink transmission can be employed (e.g., periodic CQI transmissions,periodic PUCCH transmissions, etc.). Thus, UL periodic transmitter 308can send SRS transmissions over the uplink to sound the channel over theentire system bandwidth since the SRS transmissions can be soundingsignals; therefore, at the same time as enabling uplink frequencyselective scheduling, the sounding signal can be used to compute theclosed loop corrections for UL power control. Transmissions sent by ULperiodic transmitter 308 can be received and/or employed by receivedpower monitor 204 of base station 202 in connection with sampling thechannel. Moreover, UL power adjuster 206 and/or periodic corrector 310can generate commands corresponding to such sampling.

According to an illustration, periodicity of UL transmissions sent by ULperiodic transmitter 308 of access terminal 302 can be linked to DL TPCcommand transmission cycle employed by periodic corrector 310 for accessterminal 302; hence, access terminals with differing UL transmissionperiodicity can be sent DL TPC commands with disparate transmissioncycles. Further, the periodicity of UL transmissions can correlate to anumber of bits allocated for access terminal power adjustments yieldedby periodic corrector 310 employed for a particular access terminal(e.g., access terminal 302, . . . ). For example, a mapping between thenumber of bits allocated for uplink power control correction and anuplink periodic transmission rate (e.g., SRS transmission rate, PUCCHtransmission rate, . . . ) can be predetermined. Following this example,an uplink periodic transmission rate of 200 Hz can map to 1 bit, a rateof 100 Hz can map to 1 bit, a rate of 50 Hz can map to 2 bits, a rate of25 Hz can map to 2 bits, and a rate of 0 Hz can map to x>2 bits.According to the aforementioned example, the number of bits allocatedfor the power adjustments at the access terminal becomes larger as theuplink periodic transmission rate decreases. At the limit for an uplinkperiodic transmission rate of 0 Hz (e.g., no transmission of the SRS,PUCCH, . . . ), the power adjustment can be x>2 bits, which can be thecase of open loop transmissions with closed loop adjustments on an asneeded basis.

Periodic corrector 310 can send corrections on a periodic basis tosubstantially all users in LTE_ACTIVE state associated with base station202. Pursuant to an example, users to which periodic corrector 310 sendscommands can be grouped based upon, for example, GoS requirements,DRX/DTX cycle and offset, and so forth. The transmission of the powercontrol commands for the group of users can be made by periodiccorrector 310 on a particular instantiation of the PDCCH that can bedenoted CPCCH or TPC-PDCCH. According to another illustration, periodiccorrector 310 can utilize in-band signaling to a group of users, wherethe size of the group can be greater than or equal to 1. Overheadassociated with periodic correction can be based on a number of bitsthat the correction requires and the associated control (if any)required to convey the information to the relevant access terminals.

For transfer of transmission power control (TPC) commands over the PDCCHby periodic corrector 310, a 32 bit payload and an 8 bit CRC can beemployed. For instance, 32 single-bit TPC commands in a 1 ms intervalcan be used for one PDCCH instant. Thus, 320 users in LTE_ACTIVE statecan be supported at 100 Hz using a single PDCCH on each TTI assuming FDDis employed. Accordingly, single bit corrections can be provided every10 ms, which can allow for 100 dB/s corrections. According to anotherexample, 16 dual-bit TPC commands can be employed in a 1 ms interval.Thus, 320 users can be supported in LTE_ACTIVE state with 50 Hz using asingle PDCCH on each TTI assuming FDD is employed. Hence, dual bitcorrections every 20 ms allow for 100 dB/s corrections.

Now turning to FIG. 4, illustrated is a system 400 that aperiodicallytransfers power control commands to access terminals in an LTE basedwireless communication environment. System 400 includes base station 202that communicates with access terminal 302 (and/or any number ofdiffering access terminal(s) (not shown)). Base station 202 includesreceived power monitor 204 and UL power adjuster 206, which furthercomprises an aperiodic corrector 402. Moreover, access terminal 302includes UL power manager 304, which further includes an aperiodiccommand receiver 404.

Aperiodic corrector 402 can generate a power control command directedtowards access terminal 302 on an as needed basis. For instance,aperiodic corrector 402 can transmit aperiodically when triggered by ameasurement (e.g., measurement of a condition recognized utilizing datafrom received power monitor 204 such as received power being outside ofa set margin, . . . ). Aperiodic corrector 402 can determine that anuplink power level of access terminal 302 deviates from a target at aparticular time; thus, aperiodic corrector 402 can send a command toadjust this power level in response. Further, aperiodic corrector 402can yield a single-bit correction (e.g., up/down, ±1 dB, . . . ) and/ora multi-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ).

Aperiodic command receiver 404 can obtain the corrections sent byaperiodic corrector 402 (and/or UL power adjuster 206 and/orcorresponding sector in base station 202 in general). For instance,aperiodic command receiver 404 can decipher that a particular correctionsent by the corresponding sector in base station 202 is intended foraccess terminal 302. Moreover, based upon the obtained corrections,aperiodic command receiver 404 and/or UL power manager 304 can alter anuplink power level employed by access terminal 302.

Aperiodic corrections of uplink power levels employed by access terminal302 and yielded by aperiodic corrector 402 can be trigger based. Thus,the aperiodic corrections can be associated with larger overhead ascompared to periodic corrections due to the unicast nature of theaperiodic corrections. Additionally, according to an example wheremulti-bit aperiodic corrections are employed, these corrections can bemapped to a particular instantiation of the PDCCH (e.g., in which casethe power correction can be transmitted as part of the DL assignment orUL grant) or a PDCCH/PDSCH pair (e.g., in which case the powercorrection can be transmitted stand-alone or in-band with other datatransmission).

Referring to FIG. 5, illustrated is a system 500 that employs preamblebased uplink power control in an LTE based wireless communicationenvironment. System 500 includes a sector in base station 202 thatcommunicates with access terminal 302 (and/or any number of disparateaccess terminal(s) (not shown)). As described above, the correspondingsector in base station 202 can include received power monitor 204 and ULpower adjuster 206, which can further comprise aperiodic corrector 402,and access terminal 302 can include UL power manager 304, which canfurther comprise aperiodic command receiver 404. Although not shown, itis contemplated that UL power adjuster 206 can include periodiccorrector 310 of FIG. 3 in addition to or instead of aperiodic corrector402 and/or access terminal 302 can include a periodic command receiverin addition to or instead of aperiodic command receiver 404; thus, it iscontemplated that the claimed subject matter is not limited to thefollowing illustration employing aperiodic corrector 402 and aperiodiccommand receiver 404. Moreover, UL power manager 304 can also include apreamble generator 502 that transmits a power control preamble over theuplink to the corresponding sector in base station 202 prior to uplinkdata transmission (e.g., before PUSCH/PUCCH transmission, . . . ).Additionally, UL power adjuster 206 can include a preamble evaluator 504that analyzes the received power control preamble to correct powersettings employed by access terminal 302 and send a power controlcommand over the downlink to access terminal 302. However, it iscontemplated that preamble generator 502 can be included in accessterminal 302 yet separate from UL power manager 304 and/or preambleevaluator 504 can be included in the corresponding sector in basestation 202 but separate from UL power adjuster 206.

Uplink power control can yield significant variance in SNR with burstytransmissions. To mitigate such variance, preamble transmission canenable power control commands to be provided to access terminal 302prior to uplink data transmission, where uplink data transmission canstart or resume immediately following an UL grant transmitted over thePDCCH. Upon receiving the UL grant, UL power manager 304 can employ openloop power control for setting an initial power level for sending anuplink transmission. By utilizing preamble generator 502, a transienteffect associated with the open loop power control can be mitigated whensensitive information is to be sent on the uplink over the PUCCH orPUSCH.

Preamble generator 502 can transmit a power control preamble over theuplink. The power control preamble can be a single-time SRStransmission. Such transmission of the power control preamble can bescheduled by the corresponding sector in base station 202 (and/or anetwork) explicitly or implicitly. The power control preamble sent bypreamble generator 502 enables the channel to be rapidly sounded with anuplink transmission spanning part or the entire system bandwidth (e.g.,modulo the minimum access terminal transmit bandwidth capacity, . . . ).According to an illustration, two or four hops per TTI can be achievedwith the power control preamble. Further, the power control preamble canenable the first PUCCH or PUSCH transmission after an UL grant receivedafter UL inactivity to be efficiently closed loop power controlled.

According to an example, when access terminal 302 obtains an UL grantwhile in LTE_ACTIVE_CPC (e.g., because of downlink data activity), thepower of an initial transmission to be sent over the uplink asdetermined by UL power manager 304 can be based on open loop powercontrol (e.g., without employing closed loop mechanisms). The initialopen loop setting can be noisy, and thus, can be less than optimal forthe transmit power. However, once the transmit power from the firstuplink transmission of access terminal 302 can be corrected, thereliability of the uplink transmissions can considerably improve.

To address the forgoing example, preamble generator 502 sends a powercontrol preamble that precedes transmission of information from accessterminal 302 to the corresponding sector in base station 202 (e.g., theinformation can be transmitted on PUSCH and/or PUCCH). The power controlpreamble can be communicated at a power level yielded according to openloop power control mechanisms. Preamble evaluator 504 can obtain andreview the power control preamble to quickly correct power settings ofaccess terminal 302 as evinced by the power control preamble. Forinstance, preamble evaluator 504 can generate and transmit a powercontrol command (e.g., transmission power control (TPC) command) toadjust the power level utilized by UL power manager 304 of accessterminal 302. The power control command can be a single-bit correctionand/or a multi-bit correction. Thereafter, UL power manager 304 canimplement the power control command obtained from the correspondingsector in base station 202. Further, access terminal 302 can thereaftersend uplink transmissions (e.g., PUSCH and/or PUCCH transmissions) atthe corrected open loop power level as set by UL power manager 304 inresponse to receiving the power control command.

Transmission of the power control preamble from preamble generator 502can be scheduled explicitly or implicitly by the corresponding sector inbase station 202 (and/or a scheduler (not shown) of base station 202).According to an illustration, explicit scheduling provides preamblegenerator 502 with an explicit indication to send the power controlpreamble over the uplink. Following this illustration, an UL grant(e.g., first UL grant) sent from base station 202 (e.g., over the PDCCH)can provide scheduling related data for transmitting the power controlpreamble over the uplink. Hence, the UL grant can cause preamblegenerator 502 to sound the channel in an efficient manner (e.g., two orfour hops spanning the system bandwidth in a given TTI with the powercontrol preamble sent over the uplink). After reception of the uplinktransmission by the corresponding sector in base station 202 andanalysis by preamble evaluator 504, a power correction is computed andsent on the PDCCH along with a new UL grant (e.g., second UL grant) forthe PUCCH/PUSCH transmission (e.g., which is power corrected).

By way of another example, implicit scheduling of the power controlpreamble can be utilized. Based upon access terminal 302 being in theLTE_ACTIVE_CPC substate, preamble generator 502 can recognize a priorithat a power control preamble is to be sent prior to regulartransmission of data (e.g., over the PUSCH/PUCCH). Accordingly, thecorresponding sector in base station 202 need not send two UL grants(e.g., as is the case for explicit scheduling of the power controlpreamble). Rather, an explicitly signaled UL grant can be applicable fora next hybrid automatic repeat-request (HARQ) cycle and the modulationand coding scheme (MCS) and/or resources for the power control preamblecan be default and known by both access terminal 302 and thecorresponding sector in base station 202 (e.g., retained in memory ofaccess terminal 302 and/or the corresponding sector in base station202). Thus, when employing implicit scheduling, preamble generator 502can transfer the power control preamble on predetermined resourcesinstead of with resources explicitly scheduled (e.g., as is the case forexplicit scheduling).

After the power control preamble is utilized to correct the UL powersetting, access terminal 302 can be re-allocated physical uplinkresources (e.g., by base station 202) and hence brought back to theLTE_ACTIVE state. While in LTE_ACTIVE, subsequent transmissions can bebased on corrections generated and sent by aperiodic corrector 402 toaccess terminal 302 and implemented by aperiodic command receiver 404(and/or UL power manager 304) as described herein.

Now referring to FIG. 6, illustrated is a system 600 that groups accessterminals for sending power control commands over a downlink. System 600includes the corresponding sector in base station 202 that communicateswith an access terminal 1 602, an access terminal 2 604, . . . , and anaccess terminal N 606, where N can be any integer. Each access terminal602-606 can further include a respective UL power manager (e.g., accessterminal 1 602 includes a UL power manager 1 608, access terminal 2 604includes a UL power manager 2 610, . . . , access terminal N 606includes a UL power manager N 612). Moreover, the corresponding sectorin base station 202 can comprise received power monitor 204, UL poweradjuster 206 and an access terminal (AT) grouper 614 that combines asubset of access terminals 602-606 into a group for transmitting powercontrol commands over the downlink.

AT grouper 614 can group access terminals 602-606 as a function ofvarious factors. For instance, AT grouper 614 can assign one or moreaccess terminals 602-606 to a group based upon DRX cycle and phase.Pursuant to another illustration, AT grouper 614 can allocate accessterminal(s) 602-606 to groups based upon uplink periodic transmissionrates (e.g., SRS transmission rate, PUCCH transmission rate, . . . )employed by access terminals 602-606. By combining subsets of accessterminals 602-606 into disparate groups, transmission of power controlcommands by UL power adjuster 206 on the DL over the PDCCH (or CPCCH,TPC-PDCCH) can be effectuated more efficiently (e.g., by sending powercontrol commands for multiple access terminals grouped together in acommon message). By way of example, AT grouper 614 can form groups forutilization with periodic uplink power control; however, the claimedsubject matter is not so limited.

According to an illustration, access terminal 1 602 can employ atransmission rate of 200 Hz for SRS transmission, access terminal 2 604can utilize a transmission rate of 50 Hz for SRS transmission, andaccess terminal N 606 can use a transmission rate of 100 Hz for SRStransmission. AT grouper 614 can recognize these respective transmissionrates (e.g., utilizing signals obtained via received power monitor 204,. . . ). Thereafter, AT grouper 614 can assign access terminal 1 602 andaccess terminal N 606 to a group A (along with any other accessterminal(s) that employ 100 Hz or 200 Hz transmission rates). AT grouper614 can also allocate access terminal 2 604 (and any disparate accessterminal(s) that employ 25 Hz or 50 Hz transmission rates) to a group B.It is to be appreciated, however, that the claimed subject matter is notlimited to the aforementioned illustration. Further, AT grouper 614 canassign group IDs to each of the groups (e.g., for use on the PDCCH orCPCCH). Upon assigning access terminals 602-606 to respective groups,commands sent by UL power adjuster 206 can employ downlink resourcescorresponding to a particular group associated with an intendedrecipient access terminal. For instance, AT grouper 614 and UL poweradjuster 206 can operate in conjunction to send TPC commands to multipleaccess terminals 602-606 in each PDCCH transmission. Moreover, each ULpower manager 608-612 can recognize appropriate PDCCH transmission(s) tolisten to for obtaining TPC command(s) directed thereto (e.g., basedupon corresponding group IDs, . . . ).

Turning to FIG. 7, illustrated are example transmission structures forcommunicating power control commands to access terminal groups. Forexample, the transmission structures can be employed for PDCCHtransmissions. Two example transmission structures are depicted (e.g.,transmission structure 700 and transmission structure 702); however, itis contemplated that the claimed subject matter is not limited to theseexamples. Transmission structures 700 and 702 can reduce overhead bygrouping power control commands for multiple users into each PDCCHtransmission. As illustrated, transmission structure 700 groups powercontrol commands for users in group A upon a first PDCCH transmissionand power control commands for users in group B upon a second PDCCHtransmission. Further, both the first and second PDCCH transmissionsinclude a cyclic redundancy check (CRC). Moreover, transmissionstructure 702 combines power control commands for users in groups A andB upon a common PDCCH transmission. By way of illustration, fortransmission structure 702, power control commands for users in group Acan be included in a first segment of the common PDCCH transmission andpower control commands for users in group B can be included in a secondsegment of the common PDCCH transmission.

Referring to FIG. 8, illustrated is an example timing diagram 800 for aperiodic uplink power control procedure for LTE. At 802, power controlprocedures for an access terminal in LTE_ACTIVE state are illustrated.In this state, the access terminal sends periodic SRS transmissions to abase station, and the base station replies to the periodic SRStransmissions with periodic TPC commands. As shown in the illustratedexample, the transmit power of the access terminal is corrected by asingle TPC bit transmitted periodically on the downlink. It is to benoted that the periodic SRS transmissions can be replaced by periodicCQI transmissions, periodic PUCCH transmissions, and the like. PeriodicCQI transmissions or periodic PUCCH transmissions may be less efficientfrom a channel sounding standpoint since these transmissions may notspan the entire system band; however, such transmissions can beleveraged for closed loop corrections based on UL measurements at thebase station.

At 804, an inactivity period for the access terminal is depicted. Afterthe inactivity period (e.g., predetermined or use of a thresholdperiod), the access terminal is transitioned to an LTE_ACTIVE_CPCsubstate. In this substate, the PHY UL resources are de-allocated fromthe access terminal; accordingly, it may not be possible to use closedloop power control when UL transmissions resume.

At 806, the access terminal resumes uplink transmissions. The RACH isemployed to resume uplink transmissions using an open loop estimate.Pursuant to an example, the open loop estimate can be modified inaccording to a last transmission power with some forgetting factor ifdeemed beneficial. In response to the RACH sent by the access terminal,the base station can transmit an in-band power adjustment for the accessterminal (e.g., x bit power adjustment, where x can be substantially anyinteger).

At 808, an identity of the access terminal can be verified through theRACH procedure. Further, PHY UL resource re-allocation can beeffectuated (e.g., along with SRS configuration) at 808.

At 810, the access terminal is in LTE_ACTIVE state. Hence, the accessterminal resumes periodic transmissions of the SRS. As depicted, theperiodicity of the periodic SRS transmissions at 810 differ from theperiodicity of the periodic SRS transmissions at 802; however, theclaimed subject matter is not so limited. In response to the periodicSRS transmissions, the base station sends TPC commands that in this caseaccount for 2 bits (e.g., ±1 dB, ±2 dB). Further, although notillustrated, access terminal transmissions can continue to utilize openloop corrections determined from the receive power level at the accessterminal. Therefore, the closed loop corrections can be exclusive and/oron top of the open loop corrections determined from the changes in thereceive power at the access terminal.

Now turning to FIG. 9, illustrated is an example timing diagram 900 foran aperiodic uplink power control procedure for LTE. Illustrated arepower control procedures for an access terminal in LTE_ACTIVE state.Timing diagram 900 can lack periodic uplink transmissions. Further,power corrections can be sent from a base station to the access terminalbased on power received over the PUSCH. The base station evaluates PUSCHtransmissions to determine whether to effectuate a power adjustment.Aperiodic power adjustments can be relied upon where the base stationsends a message (e.g., TPC command on UL grant) to the access terminalif a power adjustment is deemed to be needed by the base station uponevaluation of a particular PUSCH transmission. When the base stationdetermines that such power adjustment is not necessary at a particulartime for a given PUSCH transmission, the base station need not transmita TPC command at such time in response to the given PUSCH transmission(e.g., rather, an ACK can be transmitted in response to the given PUSCHtransmission, . . . ). Moreover, regardless whether a TPC command isobtained by the access terminal at a given time, the access terminal canconstantly rely on corrections based on an open loop mechanism. Further,the corrections sent by the base station can be single bit and/ormulti-bit corrections.

It is to be appreciated that a similar scheme can be employed withperiodic UL transmissions where corrections can be sent on the DL on anas needed basis. Thus, the access terminal can periodically send SRStransmissions on the uplink, which can be evaluated by the base stationto determine power adjustments to be effectuated. Thereafter, upondetermining that a power adjustment is needed at a particular time, thebase station can send a TPC command over the downlink to the accessterminal (e.g., aperiodic downlink transmission of power controlcommands).

The uplink power control procedures depicted in FIGS. 8 and 9 includecommon aspects. Namely, the notion of ΔPSD (Delta Power SpectralDensity) used for the UL data transmissions can be employed for bothperiodic and aperiodic uplink power control. The ΔPSD can provide amaximum transmit power that is allowed for a given user in order tominimize an impact to adjacent cells. The ΔPSD can evolve over time as afunction of, for example, the load indicator from adjacent cells,channel conditions, and so forth. Further, the ΔPSD can be reported tothe access terminal (e.g., in-band) when possible. In the LTE systems,the network can choose which MCS/Max data-to-pilot power ratio theaccess terminal is allowed to transmit. The initial ΔPSD, however, canbe based on the MCS in the UL grant (e.g., relationship between the ULgrant and the initial ΔPSD can be formula based). Moreover, much of theaforementioned relates to intra-cell power control. Other mechanisms forinter-cell power control (e.g., load control) can be complementary tothe mechanisms described herein.

According to another illustration, periodic and aperiodic uplink powercontrol procedures can operate in combination. Following thisillustration, periodic updates can be utilized on top of aperiodicupdates. If there are scheduled PUSCH transmissions, they can requirecorresponding PDCCH transmissions with the UL grant, and therefore, thepower control commands can be transmitted in the PDCCHs with the ULgrants. If the PDCCH is not available, for instance, for persistent ULtransmissions (e.g., not requiring the UL grants because the PHYresources are configured by higher layers), then power control commandscan be transmitted on TPC-PDCCH1. Also, if there are scheduled PDSCH onthe DL, then the power controlling of PUCCH (e.g., CQI and ACK/NAK) canbecome more critical. In such a case, the power control commands forPUCCH can be communicated on the PDCCHs with the DL assignments. For DLtransmissions without associated control or for the case of no DL dataactivity, the periodic transmissions on TPC-PDCCH2 can be used to powercontrol PUCCH. Accordingly, power control commands can be transmittedwhen needed (e.g., aperiodically) while making use of availableresources (e.g., PDCCH with UL grants for PUSCH, PDCCH with DLassignments for PUCCH, periodic TPC commands on TPC-PDCCH which can berelevant for PUCCH and persistently scheduled PUSCH, . . . ).

Now turning to FIG. 10, illustrated is an example timing diagram 1000for an uplink power control procedure for LTE that leverages a powercontrol preamble. Timing diagram 1000 relies on transmission of a powercontrol preamble scheduled from a base station (or network) in anexplicit or implicit way. At 1002, an UL grant can be sent from a basestation (or network) to an access terminal. The UL grant can betransferred by way of PDCCH transmission. At 1004, the access terminalsends a power control (PC) preamble to the base station. The powercontrol preamble can be sent at a power level determined based upon anopen loop power control mechanism. At 1006, the corresponding sector inbase station can correct the power setting of the access terminal asgleaned from the received power control preamble. The correspondingsector in base station can transmit a power control command (e.g., TPC)to the access terminal. The power control command can be a single-bitcommand and/or a multi-bit command. When employing explicit scheduling,the power control command can be sent by the corresponding sector inbase station along with a second UL grant for the access terminal totransmit data. According to another illustration, when utilizingimplicit scheduling, the power control command need not be sent with anUL grant; rather, the UL grant sent at 1002 can be utilized by theaccess terminal for transmitting data over the uplink. At 1008, theaccess terminal can transmit data over the uplink to the base station.The data can be transmitted by the access terminal with the correctedpower setting (e.g., the power level determined via open loop powercontrol and adjusted based upon the received power control command). Forinstance, the data can be sent as a PUSCH transmission and/or a PUCCHtransmission. Thereafter, although not depicted, regular closed looppower control techniques as described herein can thereafter beimplemented while the access terminal remains in LTE_ACTIVE state.

Referring to FIGS. 11-12, methodologies relating to utilizing powercontrol preambles in conjunction with controlling uplink power viaperiodic, aperiodic or a combination of periodic and aperiodiccorrections in an LTE based wireless communication environment areillustrated. While, for purposes of simplicity of explanation, themethodologies are shown and described as a series of acts, it is to beunderstood and appreciated that the methodologies are not limited by theorder of acts, as some acts can, in accordance with one or moreembodiments, occur in different orders and/or concurrently with otheracts from that shown and described herein. For example, those skilled inthe art will understand and appreciate that a methodology couldalternatively be represented as a series of interrelated states orevents, such as in a state diagram. Moreover, not all illustrated actscan be required to implement a methodology in accordance with one ormore embodiments.

With reference to FIG. 11, illustrated is a methodology 1100 thatfacilitates generating a power control preamble for utilization withpower control in a Long Term Evolution (LTE) based wirelesscommunication environment. At 1102, an uplink grant can be received froma corresponding sector in a base station. The uplink grant can becommunicated via a Physical Downlink Control Channel (PDCCH)transmission. For instance, the uplink grant can be received while anaccess terminal is in an LTE_ACTIVE_CPC state. According to anotherillustration, the uplink grant received at 1102 can be a first uplinkgrant obtained after uplink inactivity. At 1104, a power controlpreamble can be transmitted to the corresponding sector in the basestation with a power setting based on open loop power control. The powercontrol preamble can be an uplink transmission that rapidly sounds thechannel over part or an entire system bandwidth (e.g., modulo theminimum access terminal transmit bandwidth capability). For instance,the power control preamble could be a single-time Sounding ReferenceSignal (SRS) transmission. By way of another example, the power controlpreamble can be an aperiodic Channel Quality Indicator (CQI) report onan uplink data channel. The power control preamble could employ two orfour hops spanning the system bandwidth in a given transmission timeinterval (TTI). Further, the power control preamble can be an uplinktransmission that precedes uplink data transmission on a Physical UplinkShared Channel (PUSCH) and/or a Physical Uplink Control Channel (PUCCH).Moreover, the power setting utilized for transmitting the power controlpreamble can be based upon open loop power control since closed looppower control can be unavailable to the access terminal prior to beingin an LTE_ACTIVE state. Moreover, scheduling of the power controlpreamble transmission can be explicit or implicit. According to anexample where explicit scheduling is employed (e.g., transmissioncharacteristics can be explicitly indicated), the uplink grant receivedat 1102 can allocate resources, specify modulation and/or coding to beutilized, and so forth for transmission of the power control preamble.Pursuant to another illustration where implicit scheduling is utilized(e.g., transmission characteristics can be implicitly indicated),predetermined resources, modulation, coding, etc. can be leveraged fortransmission of the power control preamble; thus, the access terminalcan utilize these predetermined resources, modulation, coding, etc. forsending the power control preamble over the uplink without suchinformation explicitly being included in the uplink grant received at1102.

At 1106, a power control command can be received from the correspondingsector in the base station. The power control command can adjust thepower setting of the access terminal utilized for uplink transmission.For instance, the power control command can be a single-bit correctionand/or a multi-bit correction. Thus, the access terminal can modify thepower setting in accordance with the received power control command.Further, after the power control preamble is utilized to correct thepower setting, physical uplink resources can be re-allocated to theaccess terminal and the access terminal can transition to the LTE_ACTIVEstate. Moreover, if explicit scheduling is employed, a second uplinkgrant can be received along with the power control command, and thesecond uplink grant can be utilized to send a next uplink datatransmission. Alternatively, if implicit scheduling is utilized, thepower control command need not be accompanied by a second uplink grant;rather, the uplink grant received at 1102 can be used for sending a nextuplink data transmission (e.g., the uplink grant in such case can beapplicable for a next hybrid automatic repeat-request (HARQ) cycle).

At 1108, data can be transmitted to the base station with the adjustedpower setting. The open loop estimate for the power setting can bemodified by the correction provided as part of the power controlcommand, and the data transmission can be effectuated at this adjustedpower setting. The data transmission can be in response to the seconduplink grant obtained with the power control command if explicitscheduling is employed or the uplink grant received at 1102 if implicitscheduling is utilized. The data transmission can be a Physical UplinkShared Channel (PUSCH) transmission and/or a Physical Uplink ControlChannel (PUCCH) transmission. Pursuant to a further example, the datatransmission can relate to a set of periodic transmissions (e.g., SRStransmissions, CQI transmissions, PUCCH transmissions, . . . ).

Moreover, a power control command can be received subsequent to the datatransmission at 1108. The power control command can be sent over thedownlink upon occurrence of a triggering condition. The power controlcommand can be a single-bit command and/or a multi-bit command. Further,the power control command can be obtained via a Physical DownlinkControl Channel (PDCCH) or a PDCCH/PDSCH (Physical Downlink SharedChannel) pair. Moreover, the power control command can be received as astand-alone transmission or in-band with other data transmitted from acorresponding sector in a base station. The power setting utilized forthe data transmission at 1108 can thereafter be altered based upon thepower control command. Further, at a time when a power control commandis not obtained, such alterations to the power setting need not beeffectuated. According to another example, whether or not the powercontrol command is received and utilized to adjust the power setting,open loop power control mechanisms can be employed to alter the powersetting. By way of further illustration, data can be transmitted uponthe uplink at the power setting as altered by any type of power controlcommand, e.g., periodic and/or aperiodic.

Now turning to FIG. 12, illustrated is a methodology 1200 thatfacilitates evaluating power control preambles for employment with powercontrol in a Long Term Evolution (LTE) based wireless communicationenvironment. At 1202, an uplink grant can be transmitted to an accessterminal. The uplink grant can be sent while the access terminal is inan LTE_ACTIVE_CPC state. Moreover, the uplink grant can be sent over aPDCCH. According to an example, the uplink grant can explicitly scheduletransfer of a power control preamble from the access terminal (e.g.,transmission characteristics can be explicitly indicated); thus,following this example, the access terminal can assign resources,modulation, coding, and the like to be employed for transmission of thepower control preamble. By way of another example, predeterminedresources, modulation, coding, etc. can be utilized by the accessterminal for transmission of the power control preamble (e.g., implicitscheduling, transmission characteristics can be implicitly indicated, .. . ), and the uplink grant sent at 1202 can be applicable for an uplinkdata transmission sent by the access terminal associated with a nexthybrid automatic repeat-request (HARQ) cycle.

At 1204, a power control preamble can be received. The power controlpreamble can be sent from the access terminal at a power level set basedupon open loop power control. Further, the power level utilized by theaccess terminal for transferring the power control preamble can begleaned from the received power control preamble. The power controlpreamble can be an uplink transmission that rapidly sounds the channelover part or the full system bandwidth (e.g., modulo the minimum accessterminal transmit bandwidth capability). For instance, the power controlpreamble can employ two or four hops spanning the system bandwidth in agiven transmission time interval (TTI). For instance, the power controlpreamble could be a single-time Sounding Reference Signal (SRS)transmission. By way of another example, the power control preamble canbe an aperiodic Channel Quality Indicator (CQI) report on an uplink datachannel.

At 1206, a power control command can be generated based upon an analysisof the power control preamble, where the power control command cancorrect the power level of the access terminal. By way of illustration,the power control command can be a single-bit correction and/or amulti-bit correction to the power level employed by the access terminal.At 1208, the power control command can be transmitted to the accessterminal. When explicit scheduling is employed, a second uplink grantcan be transmitted along with the power control command, and the seconduplink grant can be utilized by the access terminal to send a nextuplink data transmission. Alternatively, when implicit scheduling isutilized, the power control command need not be accompanied by a seconduplink grant; rather, the uplink grant sent at 1202 can be used by theaccess terminal for sending a next uplink data transmission. Further,after the power control preamble is used to correct the power level,physical uplink resources can be re-allocated to the access terminal andthe access terminal can transition to the LTE_ACTIVE state. At 1210, anuplink data transmission sent from the access terminal at the correctedpower level can be received. The data transmission can be a PhysicalUplink Shared Channel (PUSCH) transmission and/or a Physical UplinkControl Channel (PUCCH) transmission. Pursuant to a further example, thedata transmission can relate to a set of periodic transmissions (e.g.,SRS transmissions, CQI transmissions, PUCCH transmissions, . . . ).

Upon receiving the uplink data transmission at 1210, a determination canbe effectuated concerning whether to adjust the power level employed bythe access terminal when sending the uplink data transmission. Accordingto an example, the power level can be compared to a target, and if thedifference exceeds a threshold, then adjustment can be triggered;otherwise, if the difference is less than the threshold, then adjustmentneed not be effectuated at that time. Further, an amount of adjustmentto the power level of the access terminal can be determined. Whendetermining that the power level should be adjusted, an aperiodic powercontrol command can be transmitted to the access terminal to alter thepower level when triggered by a measurement (e.g., measure of receivedpower level being outside a set margin, . . . ). Thus, the aperiodicpower control command can be sent on an as needed basis. The aperiodicpower control command can be a single-bit correction (e.g., up/down, ±1dB, . . . ) and/or a multi-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4dB, . . . ). Further, the aperiodic power control command can be mappedto a particular instantiation of a Physical Downlink Control Channel(PDCCH) or a PDCCH/PDSCH (Physical Downlink Shared Channel) pair.Moreover, the aperiodic power control command can be transmittedstand-alone or in-band with other data transmissions. Additionally, forexample, the aperiodic power control command can be sent via a unicasttransmission.

It will be appreciated that, in accordance with one or more aspectsdescribed herein, inferences can be made regarding employing powercontrol preambles with aperiodic power control. As used herein, the termto “infer” or “inference” refers generally to the process of reasoningabout or inferring states of the system, environment, and/or user from aset of observations as captured via events and/or data. Inference can beemployed to identify a specific context or action, or can generate aprobability distribution over states, for example. The inference can beprobabilistic—that is, the computation of a probability distributionover states of interest based on a consideration of data and events.Inference can also refer to techniques employed for composinghigher-level events from a set of events and/or data. Such inferenceresults in the construction of new events or actions from a set ofobserved events and/or stored event data, whether or not the events arecorrelated in close temporal proximity, and whether the events and datacome from one or several event and data sources.

According to an example, one or more methods presented above can includemaking inferences pertaining to recognizing whether to utilize explicitscheduling and/or implicit scheduling of uplink power control preambletransmission. By way of further illustration, an inference can be maderelated to identifying resources to be employed for uplink transmissionof a power control preamble. It will be appreciated that the foregoingexamples are illustrative in nature and are not intended to limit thenumber of inferences that can be made or the manner in which suchinferences are made in conjunction with the various embodiments and/ormethods described herein.

FIG. 13 is an illustration of an access terminal 1300 that facilitatesutilizing power control preambles with power control in an LTE basedwireless communication system. Access terminal 1300 comprises a receiver1302 that receives a signal from, for instance, a receive antenna (notshown), and performs typical actions thereon (e.g., filters, amplifies,downconverts, etc.) the received signal and digitizes the conditionedsignal to obtain samples. Receiver 1302 can be, for example, an MMSEreceiver, and can comprise a demodulator 1304 that can demodulatereceived symbols and provide them to a processor 1306 for channelestimation. Processor 1306 can be a processor dedicated to analyzinginformation received by receiver 1302 and/or generating information fortransmission by a transmitter 1316, a processor that controls one ormore components of access terminal 1300, and/or a processor that bothanalyzes information received by receiver 1302, generates informationfor transmission by transmitter 1316, and controls one or morecomponents of access terminal 1300.

Access terminal 1300 can additionally comprise memory 1308 that isoperatively coupled to processor 1306 and that can store data to betransmitted, received data, identifier(s) assigned to access terminal1300, information related to obtained power control commands, and anyother suitable information for selecting whether to implement the powercontrol commands. Memory 1308 can additionally store protocols and/oralgorithms associated with generating power control preambles forsending over an uplink and/or estimating power levels for transmissionbased upon open loop mechanisms.

It will be appreciated that the data store (e.g., memory 1308) describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable PROM (EEPROM), or flash memory. Volatile memorycan include random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).The memory 1308 of the subject systems and methods is intended tocomprise, without being limited to, these and any other suitable typesof memory.

Receiver 1302 is further operatively coupled to an UL power manager 1310that controls a power level utilized by access terminal 1300 fortransmitting via an uplink. UL power manager 1310 can set the uplinkpower level for transmitting data, control signals, and so forth via anytype of uplink channel. UL power manager 1310 can employ open loopmechanisms for selecting the uplink power level. Further, power controlcommands obtained by receiver 1302 can be utilized by UL power manager1310 to adjust the uplink power level. Additionally, UL power manager1310 and/or receiver 1302 can be coupled to a preamble generator 1312that yields power control preambles for sending over the uplink at aparticular power level (e.g., determined by UL power manager 1310 basedupon the open loop mechanism). The power control preambles generated bypreamble generator 1312 can be sent to rapidly sound the uplink channelwith an uplink transmission that spans a bandwidth of a wirelesscommunication environment. Moreover, power control commands can bereceived from a base station in response to the power control preambles,and the power control commands can be utilized by UL power manager 1310to adjust the open loop estimate of the power level as utilized for thepower control preambles. Access terminal 1300 still further comprises amodulator 1314 and a transmitter 1316 that transmits the signal to, forinstance, a base station, another access terminal, etc. Althoughdepicted as being separate from the processor 1306, it is to beappreciated that UL power manager 1310, preamble generator 1312 and/ormodulator 1314 can be part of processor 1306 or a number of processors(not shown).

FIG. 14 is an illustration of a system 1400 that facilitates analyzingpower control preambles for use with power control in an LTE basedwireless communication environment. System 1400 comprises a sector in abase station 1402 (e.g., access point, eNB, . . . ) with a receiver 1410that receives signal(s) from one or more access terminals 1404 through aplurality of receive antennas 1406, and a transmitter 1422 thattransmits to the one or more access terminals 1404 through a transmitantenna 1408. Receiver 1410 can receive information from receiveantennas 1406 and is operatively associated with a demodulator 1412 thatdemodulates received information. Demodulated symbols are analyzed by aprocessor 1414 that can be similar to the processor described above withregard to FIG. 13, and which is coupled to a memory 1416 that storesinformation related to access terminal identifiers (e.g., MACIDs, . . .), data to be transmitted to or received from access terminal(s) 1404(or a disparate base station (not shown)) (e.g., power controlcommand(s), uplink grant(s), . . . ), and/or any other suitableinformation related to performing the various actions and functions setforth herein. Processor 1414 is further coupled to a received powermonitor 1418 that assesses uplink power levels employed by accessterminal(s) 1404 based upon signals obtained at base station 1402. Forinstance, received power monitor 1418 can analyze an uplink power levelfrom a PUSCH transmission. According to another illustration, receivedpower monitor 1418 can evaluate an uplink power level from a periodicuplink transmission.

Received power monitor 1418 can be operatively coupled to a preambleevaluator 1420 that analyzes a power control preamble obtained by basestation 1402 from access terminal(s) 1404. Preamble evaluator 1420further corrects the power level utilized by an access terminal fromwhich the power control preamble originates. Thus, preamble evaluator1420 generates power control commands to be sent to adjust the accessterminal power level. Preamble evaluator 1420 can additionally beoperatively coupled to a modulator 1422. Modulator 1422 can multiplexpower control commands for transmission by a transmitter 1424 throughantenna 1408 to access terminal(s) 1404. Although depicted as beingseparate from the processor 1414, it is to be appreciated that receivedpower monitor 1418, preamble evaluator 1420 and/or modulator 1422 can bepart of processor 1414 or a number of processors (not shown).

FIG. 15 shows an example wireless communication system 1500. Thewireless communication system 1500 depicts a sector in one base station1510 and one access terminal 1550 for sake of brevity. However, it is tobe appreciated that system 1500 can include more than one base stationand/or more than one access terminal, wherein additional base stationsand/or access terminals can be substantially similar or different fromexample base station 1510 and access terminal 1550 described below. Inaddition, it is to be appreciated that base station 1510 and/or accessterminal 1550 can employ the systems (FIGS. 1-6, 13-14, and 16-17)and/or methods (FIGS. 11-12) described herein to facilitate wirelesscommunication there between.

At base station 1510, traffic data for a number of data streams isprovided from a data source 1512 to a transmit (TX) data processor 1514.According to an example, each data stream can be transmitted over arespective antenna. TX data processor 1514 formats, codes, andinterleaves the traffic data stream based on a particular coding schemeselected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot datausing orthogonal frequency division multiplexing (OFDM) techniques.Additionally or alternatively, the pilot symbols can be frequencydivision multiplexed (FDM), time division multiplexed (TDM), or codedivision multiplexed (CDM). The pilot data is typically a known datapattern that is processed in a known manner and can be used at accessterminal 1550 to estimate channel response. The multiplexed pilot andcoded data for each data stream can be modulated (e.g., symbol mapped)based on a particular modulation scheme (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM), etc.) selected forthat data stream to provide modulation symbols. The data rate, coding,and modulation for each data stream can be determined by instructionsperformed or provided by processor 1530.

The modulation symbols for the data streams can be provided to a TX MIMOprocessor 1520, which can further process the modulation symbols (e.g.,for OFDM). TX MIMO processor 1520 then provides N_(T) modulation symbolstreams to N_(T) transmitters (TMTR) 1522 a through 1522 t. In variousembodiments, TX MIMO processor 1520 applies beamforming weights to thesymbols of the data streams and to the antenna from which the symbol isbeing transmitted.

Each transmitter 1522 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel.Further, N_(T) modulated signals from transmitters 1522 a through 1522 tare transmitted from N_(T) antennas 1524 a through 1524 t, respectively.

At access terminal 1550, the transmitted modulated signals are receivedby N_(R) antennas 1552 a through 1552 r and the received signal fromeach antenna 1552 is provided to a respective receiver (RCVR) 1554 athrough 1554 r. Each receiver 1554 conditions (e.g., filters, amplifies,and downconverts) a respective signal, digitizes the conditioned signalto provide samples, and further processes the samples to provide acorresponding “received” symbol stream.

An RX data processor 1560 can receive and process the N_(R) receivedsymbol streams from N_(R) receivers 1554 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. RX dataprocessor 1560 can demodulate, deinterleave, and decode each detectedsymbol stream to recover the traffic data for the data stream. Theprocessing by RX data processor 1560 is complementary to that performedby TX MIMO processor 1520 and TX data processor 1514 at base station1510.

A processor 1570 can periodically determine which available technologyto utilize as discussed above. Further, processor 1570 can formulate areverse link message comprising a matrix index portion and a rank valueportion.

The reverse link message can comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message can be processed by a TX data processor 1538, whichalso receives traffic data for a number of data streams from a datasource 1536, modulated by a modulator 1580, conditioned by transmitters1554 a through 1554 r, and transmitted back to base station 1510.

At base station 1510, the modulated signals from access terminal 1550are received by antennas 1524, conditioned by receivers 1522,demodulated by a demodulator 1540, and processed by a RX data processor1542 to extract the reverse link message transmitted by access terminal1550. Further, processor 1530 can process the extracted message todetermine which precoding matrix to use for determining the beamformingweights.

Processors 1530 and 1570 can direct (e.g., control, coordinate, manage,etc.) operation at base station 1510 and access terminal 1550,respectively. Respective processors 1530 and 1570 can be associated withmemory 1532 and 1572 that store program codes and data. Processors 1530and 1570 can also perform computations to derive frequency and impulseresponse estimates for the uplink and downlink, respectively.

It is to be understood that the embodiments described herein can beimplemented in hardware, software, firmware, middleware, microcode, orany combination thereof. For a hardware implementation, the processingunits can be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described herein, or a combination thereof.

When the embodiments are implemented in software, firmware, middlewareor microcode, program code or code segments, they can be stored in amachine-readable medium, such as a storage component. A code segment canrepresent a procedure, a function, a subprogram, a program, a routine, asubroutine, a module, a software package, a class, or any combination ofinstructions, data structures, or program statements. A code segment canbe coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters, or memorycontents. Information, arguments, parameters, data, etc. can be passed,forwarded, or transmitted using any suitable means including memorysharing, message passing, token passing, network transmission, etc.

For a software implementation, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes can be storedin memory units and executed by processors. The memory unit can beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

With reference to FIG. 16, illustrated is a system 1600 that enablesyielding power control commands based upon power control preambles forutilization by access terminals in a wireless communication environment.For example, system 1600 can reside at least partially within a sectorin a base station. It is to be appreciated that system 1600 isrepresented as including functional blocks, which can be functionalblocks that represent functions implemented by a processor, software, orcombination thereof (e.g., firmware). System 1600 includes a logicalgrouping 1602 of electrical components that can act in conjunction. Forinstance, logical grouping 1602 can include an electrical component forsending an uplink grant over a downlink 1604. Further, logical grouping1602 can include an electrical component for obtaining a power controlpreamble sent at a power level determined from an open loop powerestimate 1606. Moreover, logical grouping 1602 can comprise anelectrical component for sending a power control command that correctsthe power level 1608. Logical grouping 1602 can also include anelectrical component for obtaining an uplink data transmission at thecorrected power level 1610. Additionally, system 1600 can include amemory 1612 that retains instructions for executing functions associatedwith electrical components 1604, 1606, 1608, and 1610. While shown asbeing external to memory 1612, it is to be understood that one or moreof electrical components 1604, 1606, 1608, and 1610 can exist withinmemory 1612.

Turning to FIG. 17, illustrated is a system 1700 that enables utilizingpower control preambles in a wireless communication environment. System1700 can reside within an access terminal, for instance. As depicted,system 1700 includes functional blocks that can represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). System 1700 includes a logical grouping 1702 of electricalcomponents that can act in conjunction. Logical grouping 1702 caninclude an electrical component for obtaining an uplink grant 1704.Moreover, logical grouping 1702 can comprise an electrical component fortransferring an uplink power control preamble at a power level selectedas a function of an open loop power control estimate 1706. Further,logical grouping 1702 can include an electrical component for obtaininga power control command that alters the power level 1708. Also, logicalgrouping 1702 can include an electrical component for transmittinguplink data at the altered power level 1710. Additionally, system 1700can include a memory 1712 that retains instructions for executingfunctions associated with electrical components 1704, 1706, 1708, and1710. While shown as being external to memory 1712, it is to beunderstood that electrical components 1704, 1706, 1708, and 1710 canexist within memory 1712.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.

What is claimed is:
 1. A method that facilitates evaluating powercontrol preambles for employment with power control in a wirelesscommunication environment, comprising: transmitting an uplink grant toan access terminal; receiving a power control preamble sent from theaccess terminal at a power level set based upon open loop power control;generating a power control command based upon an analysis of the powercontrol preamble, the power control command corrects the power level ofthe access terminal; transmitting the power control command to theaccess terminal; and receiving an uplink data transmission sent from theaccess terminal at the corrected power level.
 2. The method of claim 1,wherein the power control preamble is an uplink transmission that soundsa channel and spans part or an entire system bandwidth by employing hopsin a given transmission time interval (TTI).
 3. The method of claim 1,wherein the power control preamble is a single-time Sounding ReferenceSignal (SRS) transmission.
 4. The method of claim 1, wherein the powercontrol preamble is an aperiodic Channel Quality Indicator (CQI) reporton an uplink data channel.
 5. The method of claim 1, further comprisingexplicitly scheduling transmission of the power control preamble fromthe access terminal.
 6. The method of claim 5, further comprising:transmitting the uplink grant with explicitly specified information foruse by the access terminal when transmitting the power control preamble;transmitting a second uplink grant concurrently with the power controlcommand; and receiving the uplink data transmission sent in response tothe second uplink grant transmitted concurrently with the power controlcommand.
 7. The method of claim 1, further comprising implicitlyscheduling transmission of the power control preamble from the accessterminal.
 8. The method of claim 7, further comprising: receiving thepower control preamble sent from the access terminal in response to theuplink grant utilizing predetermined information defined for the accessterminal and a base station prior to transmission of the uplink grant;and receiving the uplink data transmission sent from the access terminalby utilizing the uplink grant sent prior to transmission of the powercontrol command.
 9. The method of claim 1, further comprisingtransmitting a power control command in response to the uplink datatransmission upon occurrence of a triggering condition.
 10. The methodof claim 1, wherein the power control command is one of a single-bitcorrection and a multi-bit correction to the power level employed by theaccess terminal.
 11. A wireless communications apparatus, comprising: amemory that retains instructions related to transferring an uplinkgrant, obtaining a power control preamble sent via an uplink at a powerlevel determined by an open loop power control mechanism, yielding apower control command that corrects the power level based upon anevaluation of the power control preamble, sending the power controlcommand via a downlink, and obtaining an uplink data transmission sentat the corrected power level; and a processor, coupled to the memory,configured to execute the instructions retained in the memory.
 12. Thewireless communications apparatus of claim 11, wherein the power controlpreamble is an uplink transmission that sounds a channel and spans partor an entire system bandwidth by employing hops in a given transmissiontime interval (TTI).
 13. The wireless communications apparatus of claim11, wherein the power control preamble is a single-time SoundingReference Signal (SRS) transmission.
 14. The wireless communicationsapparatus of claim 11, wherein the power control preamble is anaperiodic Channel Quality Indicator (CQI) report on an uplink datachannel.
 15. The wireless communications apparatus of claim 11, whereinthe memory further retains instructions related to explicitly schedulingtransmission of the power control preamble.
 16. The wirelesscommunications apparatus of claim 15, wherein the memory further retainsinstructions related to transferring the uplink grant with explicitlyspecified information for use by an access terminal when transmittingthe power control preamble, sending a second uplink grant concurrentlywith the power control command via the downlink, and obtaining theuplink data transmission sent in response to the second uplink grantsent concurrently with the power control command.
 17. The wirelesscommunications apparatus of claim 11, wherein the memory further retainsinstructions related to implicitly scheduling transmission of the powercontrol preamble.
 18. The wireless communications apparatus of claim 17,wherein the memory further retains instructions related to obtaining thepower control preamble sent in response to the uplink grant utilizingpredetermined information defined for an access terminal and a basestation prior to transfer of the uplink grant, and obtaining the uplinkdata transmission sent by utilizing the uplink grant transferred priorto transmission of the power control command.
 19. The wirelesscommunications apparatus of claim 11, wherein the memory further retainsinstructions related to transferring a power control command in responseto the uplink data transmission upon occurrence of a triggeringcondition.
 20. A wireless communications apparatus that enables yieldingpower control commands based upon power control preambles forutilization by access terminals in wireless communication environment,comprising: means for sending an uplink grant over a downlink; means forobtaining a power control preamble sent from an access terminal at apower level determined from an open loop estimate; means for sending apower control command that corrects the power level of the accessterminal, wherein the power control command is generated based upon ananalysis of the power control preamble; and means for obtaining anuplink data transmission at the corrected power level.
 21. The wirelesscommunications apparatus of claim 20, wherein the power control preambleis an uplink transmission that sounds a channel and spans part of anentire system bandwidth by employing hops in a given transmission timeinterval (TTI).
 22. The wireless communications apparatus of claim 20,wherein the power control preamble is a single-time Sounding ReferenceSignal (SRS) transmission.
 23. The wireless communications apparatus ofclaim 20, wherein the power control preamble is an aperiodic ChannelQuality Indicator (CQI) report on an uplink data channel.
 24. Thewireless communications apparatus of claim 20, further comprising: meansfor scheduling transmission of the power control preamble in an explicitmanner; means for sending the uplink grant with explicitly specifiedinformation for utilization by an access terminal when sending the powercontrol preamble; and means for sending a second uplink grantcontemporaneously with the power control command via the downlink; andmeans for obtaining the uplink data transmission sent in response to thesecond uplink grant.
 25. The wireless communications apparatus of claim20, further comprising: means for scheduling transmission of the powercontrol preamble implicitly; means for obtaining the power controlpreamble sent in response to the uplink grant utilizing predeterminedinformation set forth for an access terminal and a base station prior tosending the uplink grant; and means for obtaining the uplink datatransmission sent by utilizing the uplink grant transferred beforetransmission of the power control command.
 26. The wirelesscommunications apparatus of claim 20, further comprising means fortransferring a power control command in response to the uplink datatransmission upon occurrence of a triggering condition.
 27. Amachine-readable medium having stored thereon machine-executableinstructions for: sending an uplink grant over a downlink; obtaining apower control preamble sent from an access terminal at a power leveldetermined from an open loop estimate; sending a power control commandthat corrects the power level, wherein the power control command isgenerated based upon an analysis of the power control preamble; andobtaining an uplink data transmission at the corrected power level. 28.The machine-readable medium of claim 27, wherein the power controlpreamble is an uplink transmission that sounds a channel and spans partor an entire system bandwidth by employing hops in a given transmissiontime interval (TTI).
 29. The machine-readable medium of claim 27,wherein the power control preamble is a single-time Sounding ReferenceSignal (SRS) transmission.
 30. The machine-readable medium of claim 27,wherein the power control preamble is an aperiodic Channel QualityIndicator (CQI) report on an uplink data channel.
 31. Themachine-readable medium of claim 27, the machine-executable instructionsfurther comprise scheduling transmission of the power control preamblein an explicit manner, sending the uplink grant with explicitlyspecified information for utilization by an access terminal when sendingthe power control preamble, sending a second uplink grantcontemporaneously with the power control command via the downlink, andobtaining the uplink data transmission sent in response to the seconduplink grant.
 32. The machine-readable medium of claim 27, themachine-executable instructions further comprise scheduling transmissionof the power control preamble implicitly, obtaining the power controlpreamble sent in response to the uplink grant utilizing predeterminedinformation set forth for an access terminal and a base station prior tosending the uplink grant, and obtaining the uplink data transmissionsent by utilizing the uplink grant transferred before transmission ofthe power control command.
 33. The machine-readable medium of claim 27,the machine-executable instructions further comprise transferring apower control command in response to the uplink data transmission uponoccurrence of a triggering condition.
 34. In a wireless communicationssystem, an apparatus comprising: a processor configured to: transmit anuplink grant to an access terminal; receive a power control preamblesent from the access terminal at a power level set based upon open looppower control; generate a power control command based upon an analysisof the power control preamble, the power control command corrects thepower level of the access terminal; transmit the power control commandto the access terminal; and receive an uplink data transmission sentfrom the access terminal at the corrected power level.